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托里拆利实验是初中物理的一个重要演示实验,它对于学生理解大气压数值很重要.但笔者经过多年的教学实践发现,按教材方式做本实验有不少弊端:(1)向管内灌水银劳神费力;(2)水银在常温下易蒸发且有毒性,令人望而生畏,以致不少教师以讲代做;(3)即使做过本实验,仍有不少学生不相信是大气压支撑了玻璃管里的水银柱.究其原因:一是学生认为,大气压对槽里水银的压力是向下的,怎么说是大气压向上支撑了玻璃管水银呢?二是学生看到的不是大气压使水银柱上升的过程,而是下降的过程,再加上教师的唠唠叨叨,往往把学生搞得晕头转向.笔者利用如图1所示装置演示托里拆利实验,消除了上述弊端.本实验器材简单易得,操作方便,演示现象清晰明了:
Torricelli experiment is an important demonstration experiment for junior high school physics. It is very important for students to understand the atmospheric pressure value. However, after years of teaching practice, the author found that there are many disadvantages to this experiment according to teaching materials: (1) Irrigation into the tube (2) Mercury is evaporative and toxic at room temperature, which is daunting, and many teachers have used it instead; (3) Even after this experiment, many students did not believe that the atmospheric pressure supported the glass. The mercury column in the tube. The reason is as follows: First, the students believe that the pressure of atmospheric pressure on the mercury in the tank is downward. How do you say that the atmospheric pressure supports the glass tube of mercury? Second, the students do not see the atmospheric pressure of the mercury column. The ascending process, but the declining process, coupled with the embarrassment of teachers, often make students feel confused. The author uses the device shown in Figure 1 to demonstrate the Torelli profit experiment, eliminating the above drawbacks. The experimental equipment Simple and easy to get, convenient operation, clear demonstration phenomenon: